James f



(No Model.)

J. P. MUNSIE. DUCT FOR ELECTRIC GONDUGTO'RS.

No. 426,199. Y PatentedApr. 22. 1890.

Wmme@ vIO UNITED STATES PATENT ENCE,

LEONARD GOLES,

OF SAME PLACE.

lDUCT FOR ELECTRIC CONDUCTORS.

SPECIFICATION forming part of Letters Patent No. 426,199, dated April 22, 1890.

Application filed October 29, i889.

To @ZZ whom it may concern.-

Be it known that I, JAMES F. MUNSIE, a subject of the Queen of Great Britain, residing at Brooklyn, in the county of Kings and State ot New York, have invented certain new and useful Improvements in Duets for Electrical Conduetors and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will ep able others skilled in the art to which it appertains to make and use the same.

`My invention relates to certain new and useful improvements in ducts for electrical conductors, and more particularly to ducts designed to inclose and protect conductors conveying high-tension currents within the walls and between the partitions of buildin gs, where danger of iire is to be apprehended should an are be formed by reason of breaking of the conductor, wearing away of the insulatingcoating of neighboring conductors, or similar cause.

The object of my invention is to furnish a duct of the kind referred to, of such construction as to be indestructible by the accidental forming of an are within it, and protected at its exterior from the depredations of rats and insects, the duct being also readily manufactured from materials of moderate cost.

In the accompanying drawings, Figure l represents in longitudinal section one form of an electrical-conductor duct embodying my invention. Fig. 2 represents a cross-section thereof taken on a plane indicated by the line l l of Fig. 1. Similar numerals of reference indicate similar parts in both iigures.

The duct consists, primarily, of au inner tube 3, of capacity suitable to the number of electrical conductors tov-be conveyed, and a concentric outer tube 4t, together with an intermediate filling of powdered refractory map terial of such characterA as not to disengage gases when subjected to heat.

The inner tube 3 is made of indurated ber, or from fireandwaterresisting paper-stock, preferably made asy described in an applica tion for Letters Patent filed by me January 17, 1890, Serial No. 337,246. In said a plication one of the meausdeseribed for `pro ucing the Serial No. 328,595. (No model.)

stock referred to consists in first treating manila or other paper pulp by washing or boiling the same in a solution of common salt, sulphate of aluminum, and sulphate of zinc, until the entire mass of pulp .is completely impregnated with said solution. The solu tion, after having acted upon the pulp, is then drained off, and an equalpart, by weight, of finely-pulverized lire-clay, and an equal part, by weight, of incly-pulvcrized Port-land cement, are added to it, together with a suliicient quantity of white glue and silicate ot' soda t0 agglutin-ate and combine the whole. An 1ntimate homogeneous mixture of' these con.

stitnent parts is secured by mechaniCLl ilgtators or mixers. The mixture thus obtained may be molded into pipes, tubes, or ducts under heavy pressure. The molded products are thereupon thoroughly dried in a suitable oven, and while still hot are immersed in a hot bath of india-rubber or of fire-proof paint, (known commercially as mineral paint.)

' The hot liquid is absorbed bythe heated mass of the article plunged into it, and any existing pores are filled, thereby rendering the article thoroughly water-proof. In order (when rubber is employed) to render said rubber non-l iniiannnable the article may thereafter be subjected to the ordinary vulcanizing process.

The outer tube i is preferably of tinned sheet-iron, which, while sucient to prevent destruction by rats and insects, is inexpensive and readily made.

The intermediate filling 5 is preferably of mica, combined, if need be, with a sucient percentage of Whiting or similar-'innocuous fire-resisting powder to act a's a binding or agglutinating material to the mica, so as to make the latter pack better within the space allotted to it.

The manner ot' building up or constructing the duet is as follows: The tube `3 is placed within the tube 4, a ring-washer 6, of fire-resisting paper-pulp, being inserted at the tube ends between the two to close the intervening space. Powdered mica or powdered mica and Whiting is then poured into the intervening space, and at intervals additional rings, as 7,

`oiiire-resisting paperepulp are inserted and forced down upon the powdered material to firmly compact it. When the annular space is lled nearly to the oppositeend of the duet, additional rings similar to 6 7 are inserted at said ends to retain the paclling and close the annular space.

The several rings referredito, besides serv,- ing the function of packers, also strengthen the general structure and increase the durability of the duct. v

Having thusI described my invention, what i' claim is l. .An electric-wirednct consisting of 'con .centric tubes having an intermediate filling of powdered fire-resisting materiaL' substan-` tially as described. l

2. An eleetrie-wire duct consisting of an y inner tube of tire-and-water-resisting material, l

an outer tube of metal, and an intermediate filling consisting principally of f powdered mica, substantially as described. y 3. An electricfwire duct consisting of an innertube of fire-an d-water-resisting material,

ing-rings for said material, substantially as described.

l An electric-wire duct consisting of an inner tube of fire-and-water-resisting material,

an 'outer tube of Ytin, an intermediate filling consisting principally yof powdered micaztnd'` packing-rings for said lilling, substantially asv described. l In testimony whereof Iaix my signature in presence of two witnesses;

Witnesses JOHN C. "Pitman, D. G. STUART.

'JAMES FQMUNsiE.' 

